1. Study population
In total 8,295 children (male: 4,032, female: 4,263; age: 3~18 years old) visited two pediatric allergic clinics for allergy symptoms between 1998 and 2019. Table 1 shows the diagnosis of the subjects in this study and allergic rhinitis was most common in the subjects (Allergic rhinitis: 2,295, Atopic dermatitis: 2,259, asthma: 1,736, and the others: 2,005).